Shazam, for me, (maybe Maps is a close second) the most magical app on my phone, the thing from the future that I would never have imagined being real if you told the Me from 20 years ago. It is sometimes so fast, under 5 seconds. Just wonderfully great. It makes me feel superhuman. It really is one of those extra sensory powers that we have recently gained with these universal gadgets in our pockets.
It really is a marvel in its simplicity and reliance on "older" concepts (frequency transforms, hashing, etc.) as opposed to any crazy ML (AFAIK) -- surprisingly not that cutting edge. And I'm not knocking that / there's nothing wrong with the age of a technique. If it's useful, it's useful. It's incredible. It's a perfect example of bringing together several previously somewhat disparate domains of math with just the right application and an Internet-connected smartphone. In that regard, it's a bit crazy to think that the math to enable Shazam has probably been around for...several decades? Just took a stroke of ingenuity to bring it all together.
